The U.S. Department of Agriculture is responsible for promoting dietary and nutritional guidelines for Americans. But it also puts its money where its mouth (and stomach) is: The USDA's cafeteria is the healthiest place to eat near the Mall — and even offers free nutritional advice once a week.

The cafeteria, in the USDA's south building, on Independence Avenue SW, looks like many other food courts and one-stop lunch shops in Washington, with deli stations and sushi counters surrounding a by-the-pound salad bar and hot-dish serving station, where different cuisines rotate onto the menu every day. But it's more affordable than most: You can fill a recyclable container with as much food as you want from the salad and hot bars for $7.20 per pound at lunch. The labels do more than just name what's in the chafing dish below — they note whether dishes are free of cholesterol and trans fats, low in saturated fat, or a good source of certain vitamins. Every ingredient is listed, along with the amount of protein, sodium, calories and fat per serving.

This is all by design: When the USDA renovated its cafeterias in 2013, the tender for the new operator mandated healthful food, including no deep-fat fryers.

I probably would have scooped some of the Hong Kong noodles into my carryout container anyway — pan-fried egg noodles with chile paste, garlic, onion and veggies — but knowing they had zero cholesterol and were low in fat and saturated fat might have been the nudge I needed, especially when paired with the tofu in garlic sauce. I added some wok-seared vegetables and a scoop of ginger chicken.

But if you're still wondering exactly how healthful your choices are, there's an in-house expert who can give you all the help you need. Every Wednesday from 11:30 a.m. to 1 p.m., you'll find Evangelina DiSpirito, a registered dietitian who works for cafeteria operators I.L. Creations, leading a sampling of different healthful meal options, or hosting a free-form “Ask a Dietitian” event. “People say, 'Is this healthy?' and I can provide science-based nutrition advice,” DiSpirito explains. Often, “There's a frequent misconception that anything with carbs isn't healthy. We'll have a demonstration with quinoa or brown rice, and people say, ‘Oh, I thought all carbs were bad.’ ”

Sometimes, people just ask her to evaluate what's on their plate. After lunch, I emailed her and asked for her opinion on my meal, which I thought was relatively healthful. DiSpirito said it had “health potential,” but recommended swapping proportions. “Instead of having the noodles take up a majority of the plate, have the vegetables take up more space. ... However, in general, filling your plate with more vegetables and smaller portions of starches will create a more well-balanced plate for good health.”

DiSpirito says that when people ask for her advice on their lunches, “more fruits and vegetables” is almost always her first suggestion.

Of course, “healthful” doesn't always translate to “delicious” — the ginger chicken was a little flabby, the veggies could have used a little more flavor — but it was filling and affordable, and certainly more interesting than the food trucks lining nearby sidewalks. The cafeteria itself, with a mix of long tables and cushy booths, is an airy place to dine.

Word of warning: Although the cafeteria is open to everyone, members of the public have to pass through a metal detector and have their bags X-rayed at the front entrance. It's also a popular destination for visiting school groups, who tend to head right for the pizza and burrito counters, which makes DiSpirito sigh: “Sometimes I see them with fruits and vegetables on their plates, so that's good.”